what if _name_=_main_ : means in python

Every module in python has a special attribute called __name__ . The value of __name__  attribute is set to '__main__'  when module run as main program. Otherwise the value of __name__  is set to contain the name of the module.
Consider the following code for better understanding.

# file my_module.py foo = 100 def hello():     print("i am from my_module.py") if __name__ == "__main__":     print("Executing as main program")     print("Value of __name__ is: ", __name__)     hello()

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# file my_module.py   foo = 100   def hello():     print("i am from my_module.py")   if __name__ == "__main__":     print("Executing as main program")     print("Value of __name__ is: ", __name__)     hello()

Here we have defined a new module my_module . We can execute this module as main program by entering the following code

python my_module.py

1	python my_module.py

Expected Output:

Executing as main program Value of __name__ is: __main__ i am from my_module.py

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Executing as main program Value of __name__ is: __main__ i am from my_module.py

here we are creating a new module and executing it as main program so the value of __name__ is set to '__main__' . As a result if condition satisfies and hello()  function gets called.
Now create a new file called using_module.py  and write the following code

import my_module print(my_module.foo) my_module.hello() print(my_module.__name__)

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import my_module   print(my_module.foo) my_module.hello()   print(my_module.__name__)

Expected Output:

100 i am from my_module.py my_module

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100 i am from my_module.py my_module

As you can see now if statement in my_module  fails to execute because the value of __name__  is set to 'my_module' .